Sr-Nd-Pb isotopic systematics of crustal rocks from the western Betics (S. Spain): Implications for crustal recycling in the lithospheric mantle beneath the westernmost Mediterranean

Varas-Reus, Maŕia Isabel; Garrido, Carlos J.; Marchesi, Claudio; Bosch, Delphine; Acosta-Vigil, Antonio; Hidas, Károly; Barich, Amel; Booth‐Rea, Guillermo

doi:10.1016/j.lithos.2016.10.003

Cited by 19 publications

(9 citation statements)

References 78 publications

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“…Similar conclusions have been reached about the mafic eclogites from the Nevado‐Filabride Complex (Puga et al., 2011). A Late Oligocene‐Miocene HT event is recorded in the rim of zircons with ages around 25–20 Ma, close to the age of undeformed anatectic granites cross‐cutting both the peridotite bodies and some crustal units in the Betics and Rif (Frasca et al., 2017; Marchesi et al., 2012; Rossetti et al., 2010; Sánchez‐Rodrı́guez & Gebauer, 2000; Varas‐Reus et al., 2017). For further discussions about the timing of exhumation of the Ronda peridotite s.l., the readers may also refer to Bessière et al.…”

Section: Geological and Geodynamic Settingsmentioning

confidence: 96%

Exhumation of the Ronda Peridotite During Hyper‐Extension: New Structural and Thermal Constraints From the Nieves Unit (Western Betic Cordillera, Spain)

et al. 2021

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Section: Geological and Geodynamic Settingsmentioning

confidence: 96%

Exhumation of the Ronda Peridotite During Hyper‐Extension: New Structural and Thermal Constraints From the Nieves Unit (Western Betic Cordillera, Spain)

et al. 2021

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“…This nappe stack shows southwards vergence in the Betics, after undoing paleomagnetic rotations (Lonergan, 1993). Subduction of the oceanic Tethys lithosphere probably did not initiate until the Neogene, as evidenced by a Tethyan Flysch Sr‐Nd‐Pb isotopic signature in the Middle to Late Miocene Alboran volcanic arc that is not present in Paleogene volcanic rocks and dikes crosscutting the Alpujarride‐Malaguide thrust stack (Varas‐Reus et al., 2017). There is furthermore no evidence of a developed Palaeogene volcanic arc domain related to this thickening event in the Alboran and Kabylian domains (e.g., Lustrino et al., 2011).…”

Section: Geodynamic and Geological Settingsmentioning

confidence: 99%

Two Cenozoic Extensional Phases in Mallorca and Their Bearing on the Geodynamic Evolution of the Western Mediterranean

et al. 2021

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We study the structure of the Llevant ranges in Mallorca with special emphasis on the Cenozoic extensional evolution of the island, which we integrate in a new geodynamic model for the Westernmost Mediterranean. Mallorca underwent two Cenozoic rifting phases in the Oligocene and Serravallian, before and after the development of its Foreland Thrust Belt (FTB). The first extensional event produced Oligocene semigrabens (≈29–23 Ma) that were inverted during the Early‐Middle Miocene (19–14 Ma) WNW‐directed FTB development. The second rifting event produced the extensional collapse of the Mallorca FTB during the Serravallian (≈14–11 Ma). This later rifting was polyphasic, with two orthogonal extensional systems, producing first NE‐SW, and then NW‐SE extension. The Oligocene extension affected a major part of the Western Mediterranean, opening the Liguro‐Provençal and other basins after the collapse of the Palaeogene AlKaPeCa orogen, and Mallorca, its former hinterland. Continued plate convergence nucleated a new subduction system in the Early Miocene that initiated along the Ibiza transform, producing the Mallorca WNW‐directed FTB and subduction of the South‐East Iberian passive margin. This process individualized the Betic‐Rif slab and initiated its westward retreat. Serravallian extension occurred at the northern edge of the subduction system coeval to the Algero‐Balearic basin opening. Extension initiated toward the SW direction of slab tearing and later rotated to a NW‐SE direction, probably in response to flexural and isostatic rebound. Through these processes the Alboran domain archipelago was driven toward the southwest until the Late Miocene, contributing to the present isolation of Mallorca from its Betic hinterland.

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“…Upwelling of hot mantle material coupled to extension potentially eroded the base of the SCLM and resulted in the formation of large amounts of SiO2-undersaturated, high-Mg# alkaline melts at the N-African margin (Duggen et al, 2005;Duggen et al, 2009;Varas-Reus et al, 2017). During influx of such melts in refractory peridotites at mantle conditions (>1000 °C and 1.0 GPa), the first reaction to take place is the dissolution of orthopyroxene and simultaneous crystallization of clinopyroxene and olivine (Shaw, 1999;Shaw et al, 2005;Lambart et al, 2012;Marchesi et al, 2017).…”

Section: Role Of the Step Fault In Melt-rock Interaction In The Shallmentioning

confidence: 99%

Lithosphere tearing along STEP faults and synkinematic formation of lherzolite and wehrlite in the shallow subcontinental mantle

Hidas¹,

Garrido²,

Booth‐Rea³

et al. 2019

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Abstract. Subduction-Transform Edge Propagator (STEP) faults are the locus of continual lithospheric tearing at slab edges, resulting in sharp changes in the lithospheric and crustal thickness and triggering lateral and/or near-vertical mantle flow. However, the mechanisms at the lithospheric mantle scale are still poorly understood. Here, we present the microstructural study of olivine-rich lherzolite, harzburgite and wehrlite mantle xenoliths from the Oran volcanic field (Tell Atlas, NW Algeria). This alkali volcanic field occurs along a major STEP fault responsible for the Miocene westward slab retreat in the westernmost Mediterranean. Mantle xenoliths provide a unique opportunity to investigate the microstructures in the mantle section of a STEP fault system. The microstructures of mantle xenoliths show a variable grain size ranging from coarse granular to fine-grained equigranular textures uncorrelated with modal variations. The major element composition of the mantle peridotites provides temperature estimates in a wide range (790–1165 °C) but in general, the coarse-grained and fine-grained peridotites suggest deeper and shallower provenance depth, respectively. Olivine grain size in the fine-grained peridotites depends on the size and volume fraction of the pyroxene grains, which is consistent with pinning of olivine grain growth by pyroxenes as second phase particles. In the coarse-grained peridotites, well-developed olivine crystal preferred orientation (CPO) is characterized by orthorhombic and [100]-fiber symmetries, and orthopyroxene has a coherent CPO with that of olivine, suggesting their coeval deformation by dislocation creep at high-temperature. In the fine-grained microstructures, along with the weakening of the fabric strength, olivine CPO symmetry exhibits a shift towards [010]-fiber and the [010]- and [001]-axes of orthopyroxene are generally distributed subparallel to those of olivine. These data are consistent with deformation of olivine in the presence of low amounts of melts and the precipitation of orthopyroxenes from a melt phase. The bulk CPO of clinopyroxene mimics that of orthopyroxene via a topotaxial relationship of the two pyroxenes. This observation points to a melt-related origin of most clinopyroxenes in the Oran mantle xenoliths. The textural and geochemical record of the peridotites are consistent with interaction of a refractory harzburgite protolith with a high-Mg# melt at depth (resulting in the formation of coarse-grained clinopyroxene-rich lherzolite and wehrlite), and with a low-Mg# evolved melt in the shallow subcontinental lithospheric mantle (forming fine-grained harzburgite). We propose that pervasive melt-peridotite reaction – promoted by lateral and/or near-vertical mantle flow associated with lithospheric tearing – resulted in the synkinematic crystallization of secondary lherzolite and wehrlite and played a key effect on grain size reduction during the operation of the Rif-Tell STEP fault. Melt-rock reaction and secondary formation of lherzolite and wehrlite may be widespread in other STEP fault systems worldwide.

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Sr-Nd-Pb isotopic systematics of crustal rocks from the western Betics (S. Spain): Implications for crustal recycling in the lithospheric mantle beneath the westernmost Mediterranean

Cited by 19 publications

References 78 publications

Exhumation of the Ronda Peridotite During Hyper‐Extension: New Structural and Thermal Constraints From the Nieves Unit (Western Betic Cordillera, Spain)

Exhumation of the Ronda Peridotite During Hyper‐Extension: New Structural and Thermal Constraints From the Nieves Unit (Western Betic Cordillera, Spain)

Two Cenozoic Extensional Phases in Mallorca and Their Bearing on the Geodynamic Evolution of the Western Mediterranean

Lithosphere tearing along STEP faults and synkinematic formation of lherzolite and wehrlite in the shallow subcontinental mantle

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